Alarm suspend system

ABSTRACT

An alarm suspend system utilizes an alarm trigger responsive to physiological parameters and corresponding limits on those parameters. The parameters are associated with both fast and slow treatment times corresponding to length of time it takes for a person to respond to medical treatment for out-of-limit parameter measurements. Audible and visual alarms respond to the alarm trigger. An alarm silence button is pressed to silence the audible alarm for a predetermined suspend time. The audible alarm is activated after the suspend time has lapsed. Longer suspend times are associated with slow treatment parameters and shorter suspend times are associated with fast treatment parameters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/476,725, filed May 21, 2012, now U.S. Pat. No. 8,547,209, and titled“Alarm Suspend System,” which is a continuation of U.S. patentapplication Ser. No. 12/510,982 filed Jul. 28, 2009 now U.S. Pat. No.8,203,438, and titled “Alarm Suspend System,” which claims prioritybenefit under 35 U.S.C. §119(e) to U.S. Provisional Patent ApplicationSer. No. 61/084,615, filed Jul. 29, 2008, titled “Alarm ManagementSystem.” All of the above referenced applications are herebyincorporated by reference in their entireties herein.

BACKGROUND

Pulse oximetry for measuring constituents of circulating blood hasachieved acceptance in a wide variety of medical applications, includingsurgical wards, intensive care and neonatal units, general wards, homecare, physical training, and virtually all types of monitoringscenarios. A pulse oximeter generally includes a two-wavelength opticalsensor applied to a patient, a monitor for processing sensor signals anddisplaying results and a patient cable electrically interconnecting thesensor and the monitor. The monitor typically provides a numericalreadout of physiological parameters such as oxygen saturation (SpO₂) andpulse rate (PR). Advanced physiological monitors utilize multiplewavelength sensors and enhanced measurement capabilities to providereadouts of additional parameters, such as carboxyhemoglobin (HbCO),methemoglobin (HbMet) and total hemoglobin (Hbt).

Pulse oximeters capable of reading through motion induced noise aredisclosed in at least U.S. Pat. Nos. 6,770,028, 6,658,276, 6,650,917,6,157,850, 6,002,952, 5,769,785 and 5,758,644; low noise pulse oximetrysensors are disclosed in at least U.S. Pat. Nos. 6,088,607 and5,782,757; all of which are assigned to Masimo Corporation, Irvine,Calif. (“Masimo”) and are incorporated by reference herein.

Physiological monitors and corresponding multiple wavelength opticalsensors are described in at least U.S. patent application Ser. No.11/367,013, filed Mar. 1, 2006 and titled Multiple Wavelength SensorEmitters and U.S. patent application Ser. No. 11/366,208, filed Mar. 1,2006 and titled Noninvasive Multi-Parameter Patient Monitor, bothassigned to Masimo Laboratories, Irvine, Calif. (Masimo Labs) and bothincorporated by reference herein.

Further, physiological monitoring systems that include low noise opticalsensors and pulse oximetry monitors, such as any of LNOP® adhesive orreusable sensors, SofTouch™ sensors, Hi-Fi Trauma™ or Blue™ sensors; andany of Radical®, SatShare™, Rad-9™, Rad-5™, Rad-5v™ or PPO+™ Masimo SET®pulse oximeters, are all available from Masimo. Physiological monitoringsystems including multiple wavelength sensors and correspondingnoninvasive blood parameter monitors, such as Rainbow™ adhesive andreusable sensors and RAD-57™ and Radical-7™ monitors for measuring SpO₂,pulse rate (PR), perfusion index (PI), pleth variability index (PVI),signal quality, HbCO and HbMet among other parameters are also availablefrom Masimo.

SUMMARY OF THE INVENTION

Monitor alarms are triggered by out-of-limit parameters and systemfailures, the latter including monitor or sensor failures or impropersensor placement, to name a few. Alarms can be visual, audible or both.Alarms can also have different levels of priority, which are reflectedin the type of visual and audible alarms. In an embodiment, parametersexceeding limits such as low SpO₂, high HbCO, high HbMet and low andhigh BPM trigger high priority alarms. System failures due to sensoroff, no sensor or defective sensor also trigger high priority alarms.Parameters exceeding limits such as high SpO₂, low and high PI, low andhigh PVI, for example, trigger medium priority alarms. Parametersexceeding limits such as low HbCO and low HbMet along with a system lowbattery indication are examples of low priority alarms.

An audible alarm may be temporarily suspended by pressing an alarmsilence button so as to prevent unnecessary disturbance to the patientand distraction of the caregiver. During alarm suspension, visual alarmsremain active. If an alarm condition persists after a predeterminedalarm suspend period, the audible alarm resumes. The alarm suspendperiod is typically long enough to give a caregiver sufficient time tointervene with appropriate patient treatment yet short enough to ensurethat patient health is not endangered if intervention is ineffective.For conventional pulse oximetry, an alarm suspend may be, for example, amaximum of 120 seconds.

Alarm suspension on advanced blood parameter monitors is problematic.With conventional pulse oximetry, treatment for abnormal parametermeasurements can be quickly applied and a patient response is typicallyfast. For example, a treatment for low oxygen saturation is theapplication of an oxygen mask or an increase in oxygen flow. Bycontrast, the duration of treatment for parameters measured by advancedmonitors is highly dependent on the alarm-triggering parameter. Forexample, the treatment for high methemoglobin is the injection ofmethylene blue, and the patient response to such an injection is slow.When patient treatment time exceeds the maximum alarm suspend period, anaudible alarm will constantly reactivate. Thus, a single alarm suspendduration for all parameters is inadequate to cope with the manydifferent types of parameters measured by advanced monitors.

One aspect of an alarm suspend system for silencing the alarms is analarm trigger responsive to any of various parameters and predeterminedlimits corresponding to the parameters, where the parameters arepartitioned according to treatment time, i.e. the relative length oftime it takes for a person to respond to medical treatment for aparameter measurement outside of the predetermined limits. An audiblealarm is responsive to the alarm trigger. An alarm silence button isactuated so as to suspend the audible alarm. A timer tracks the durationof the suspended alarm and is initiated by actuation of an alarm silencebutton. The timer retriggers the audible alarm after the timed durationhas lapsed/expired. In an embodiment, a long duration suspend time isassociated with slow treatment parameters and a short duration suspendtime is associated with fast treatment parameters. Fast treatmentparameters may include, for example, parameters relating to normal bloodhemoglobin constituents and slow treatment parameters may includeparameters relating to abnormal blood hemoglobin constituents.

In various embodiments, a short duration suspend time is less than orequal to about two minutes and a long duration suspended time is greaterthan about two minutes. A default duration associated with the fasttreatment parameters is about two minutes and a default durationassociated with the slow treatment parameters is about fifteen minutes.The alarm suspend system may also have an alarm suspend overrideresponsive to a predetermined unit change in the parameter triggering asuspended alarm. The override results in reactivation of the suspendedalarm. A physiological monitor having an alarm suspend system may alsohave a pop-up window that appears on the monitor display in response toactuation of the silence button, where the pop-up window presents achoice of alarm suspend durations.

Another aspect of an alarm suspend system is a partition of measuredparameters into at least a first group and a second group. An audiblealarm is triggered if at least one parameter is outside of predeterminedlimits. The audible alarm is suspended in response to a silence request.A first duration is associated with the first group and a secondduration is associated with the second group. The audible alarm isreactivated after at least one of the first duration and the secondduration. The first duration may be set so as to generally correspond toa first range of treatment times for the first group of parameters.Likewise, the second duration may be set so as to generally correspondto a second range of treatment times for the second group of parameters,where the first range of treatment times and the second range oftreatment times are non-overlapping.

In various embodiments, suspended audible alarms are overridden if thetriggering parameter has greater than a predetermined unit change beforethe suspended alarm expires according to either the first duration orthe second duration. The first and second groups are defined in relationto normal hemoglobin measurements abnormal hemoglobin measurements,respectively. The first duration is set to be less than or equal to twominutes and the second duration is set to be greater than two minutes,with default durations of about two minutes corresponding to the firstgroup and about fifteen minutes corresponding to the second group. In anembodiment, a pop-up window for a monitor display is constructed and thefirst duration and the second duration are selected from a range ofdurations presented within the pop-up window.

A further aspect of an alarm suspend system deactivates an audible alarmfor one of a short duration and a long duration according to thealarm-triggering parameter. A first group of parameters is associatedwith the short duration and a second group of parameters is associatedwith the long duration. The first group and the second group arepartitioned according to a fast treatment time and a short treatmenttime associated with the parameters. An override reactivates the audiblealarm if the trigger parameter changes more than a predetermine amountduring the corresponding duration. In various embodiments, the firstgroup comprises parameters related to the measurement of normalhemoglobin and the second group comprises parameters related to themeasurement of abnormal hemoglobin. The long duration is greater thanabout 120 seconds and the short duration is less than or equal to about120 seconds. A pop-up window for the display allows selection of thelong duration and the short duration in response to the silence button.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a physiological measurement systemutilizing an alarm suspend system;

FIG. 2 is a detailed block diagram of a physiological measurement systemutilizing an alarm suspend system;

FIG. 3 is a flow diagram of an alarm suspend system embodiment;

FIG. 4 is a state diagram of an alarm suspend system embodiment; and

FIG. 5 is an illustration of an alarm suspend pop-up window.

DETAILED DESCRIPTION

FIG. 1 illustrates a physiological measurement system 100 that utilizesan alarm suspend system. The physiological measurement system 100 has anoninvasive sensor 105 attached to a tissue site 10, a physiologicalmonitor 101, and an interface cable 109 interconnecting the monitor 101and the sensor 105. The physiological measurement system 100 mayincorporate pulse oximetry in addition to advanced features, such as amultiple wavelength sensor and advanced processes for determiningphysiological parameters other than or in addition to those of pulseoximetry, such as carboxyhemoglobin, methemoglobin and total hemoglobin,as a few examples.

The monitor 101 has a front panel 110 providing a display 120, touchkeys 130, controls 140, a speaker 150, a sensor port 160 and statusindicators 170. The display 120 shows parameter readouts, limits andwaveforms among other items. The display 120 also has touch key icons122 that indicate touch key 130 functions. The speaker 150 provides anaudible alarm in response to physiological measurements that violatepreset conditions, such as an out-of-limit parameter, as well as systemfailures, such as a low battery condition. The controls 140 include analarm silence button 144 that is pressed to temporarily suspendout-of-limit parameter alarms and system alarms, such as low battery.The display 120 provides visual alarms, which include a bell-shapedalarm status indicator 124 that illuminates during an alarm conditionand parameter readouts 210 and limits 220 that flash when parameters areout-of-limit. Status indicators 170 also provide visual alarms. Whenthere are multiple alarm conditions, the parameter displays 202 indicateparameters with the highest alarm priority. Touch keys 130 andcorresponding icons 122 include an alarm menu access button for settingalarm conditions, such as high or low alarm limits for SpO₂, HbCO,HbMet, PR and PI. The alarm silence button 144 is pressed to temporarilysuspend audible alarms. Advantageously, an alarm suspend system providesa parameter-dependent variation in the alarm suspend duration, asdescribed below, utilizing a common silence button or other suspendinitiator.

FIG. 2 illustrates a physiological measurement system 200 including aphysiological monitor 201, a sensor 205 and an interface cable 209. Thesensor 205 is attached to a tissue site, such as a finger 10, andincludes a plurality of emitters 206 irradiating the tissue site 10 withmultiple wavelengths of light. The sensor 205 also includes one or moredetectors 208 capable of detecting the light after attenuation by thetissue site 10. The sensor 205 transmits optical radiation atwavelengths other than or including the red and infrared wavelengthsutilized in pulse oximeters. The monitor 201 inputs a correspondingsensor signal 211 and determines the relative concentrations of bloodconstituents other than or in addition to the “normal” blood hemoglobinconstituents HbO₂ and Hb, including “abnormal” blood hemoglobinconstituents HbCO, HbMet and blood related parameters such as fractionaloxygen saturation, total hemoglobin and blood glucose to name a few.

As shown in FIG. 2, the monitor 201 has a front-end signal conditioner210, an A/D converter 220, emitter drivers 230, D/A converters 240 and adigital signal processor (“DSP”) 250. In general, the emitter drivers230 convert digital control signals, via the D/A converters 240, intoanalog drive signals capable of driving the sensor emitters 206. Thefront-end signal conditioner 210 converts, via the A/D converter 220,composite analog intensity signal(s) from light sensitive detector(s)208 into digital data input to the DSP 250. The emitter drivers 230 andfront-end signal conditioner 210 communicate with the sensor 205 via theinterface cable 209.

Also shown in FIG. 2, the monitor 201 has an instrument manager 260 anda user interface 280. The user interface 280 includes one or moredisplays 282, alarms 284 and user input/output (I/O) 286. The instrumentmanager 260 communicates with the DSP 250 to receive parameter data andto present that data on the display 282. The instrument manager 260 mayalso store and display historical or trending data related to one ormore of the measured parameters or combinations of the measuredparameters. The instrument manager 260 also controls audible and visualalarms and indicators 284. The instrument manager 260 responds touser-actuated keys and communicates with external devices via variousI/O ports 286. Further, the instrument manager 260 executes alarmsuspend firmware 270 so as to respond to an alarm silence button press288, as described in detail with respect to FIGS. 3-4.

FIG. 3 generally illustrates an alarm suspend system 300. Alarm triggersinclude system failures 338 and out-of-limit parameters 318. Triggeredalarms 340 may be audible, visual or both, and may vary according topriority 342. Audible alarms may be generated by a monitorfront-panel-mounted speaker 150 (FIG. 1) and may vary in loudness, pitchand sound pattern. Visual alarms may include parameter labels, parameternumerics, symbols and status lights, which can flash and vary in color.

As shown in FIG. 3, measured parameters 312 are compared 310 to defaultor user-specified limits 314. An out-of-limit condition 318 triggers analarm 340. An alarm suspend 328 is user-initiated by a silence request322. This may be a press of a silence button 144 (FIG. 1) on a monitorfront panel 110 (FIG. 1). In an embodiment, the alarm suspend 328silences audible alarms and modifies the display of visual alarms. Thealarm suspend 328 is based on a timer 320, which ends the alarm suspend328 after a predetermined duration 324. The duration 324 may be afunction of the out-of-limit parameter 312. In an advantageousembodiment, the duration 324 relates to, or is a function of, thetreatment time for the alarm-triggering parameter so as to avoidnuisance alarms while maintaining alarm integrity.

FIG. 4 illustrates an alarm suspend embodiment 400 that operatesindependently for each measured parameter that can trigger an alarm. Analarm is initially off 410. The alarm remains off as long as theparameter is within its set limits 412. If a parameter is measuredoutside of its set limits 414, an alarm is triggered 420. The alarm mayaudible, visual or both audible and visual. A user can request tosilence the alarm by pressing an alarm silence button 144 (FIG. 1), forexample. The silence request 422 suspends the alarm 430 which turns offaudible alarms but, in an embodiment, does not deactivate visual alarms.The audible alarm remains suspended 430 for a predetermined duration432. When the suspend duration has passed, the alarm suspend expires 434and audible alarms are once again activated 420. The alarm remains on428 until the triggering parameter is within limits 424 or a user onceagain requests silence 422. The alarm suspend 430 deactivates if themeasured parameter becomes within limits 438, such as when the patientcondition improves, or if no physiological data is detected 439, such asno sensor, sensor off, no cable or malfunctioning sensor situations, toname a few. Also, if the measured parameter changes during the alarmsuspend 430 by a sufficient out-of-limit amount, an override 436reactivates the audible alarms 420.

In an alarm suspend system embodiment, parameters are classifiedaccording to the typical time it takes for medical treatment totransition an out-of-limit measurement to a within-limit measurement.Suspend durations 324 (FIG. 3) are set accordingly. For example, in atwo-tier embodiment, relatively slow treatment parameters, such asHbMet, HbCO, Hbt and PVI, are assigned relatively long suspenddurations. Similarly, relatively fast treatment parameters, such as SpO₂and PR, are assigned relatively short suspend durations. In anembodiment, the alarm suspend duration is adjustable for each individualparameter, including 2, 5, 10, 15, 20, 25 and 30 minutes for slowtreatment parameters, with a default of 15 minutes; and 30, 60, 90 and120 seconds for fast treatment parameters, with a default of 120seconds. These alarm features are only active when alarm limits havebeen set. Other alarm features apply to both slow treatment and fasttreatment parameters. For example, an alarm delay of 0, 5, 10 or 15seconds applies to all enabled parameters.

In an embodiment, an override 436 occurs if slow treatment parameterssuch as HbCO, HbMet or PVI increase or Hbt decreases by a certain unitchange during the alarm suspend duration. The unit change is adjustablefor each parameter, such as from 1-15 in increments of 1. TABLE 1 showsa default embodiment of override unit changes for these parameters.

TABLE 1 Override Unit Changes for Selected Parameters Parameter UnitChange Direction HbCO 5 Increase HbMet 2 Increase Hbt 2 Decrease PVI OFFIncrease

FIG. 5 illustrates an alarm suspend window 500 that provides a “pop-up”display so that a monitor user may manually enter an alarm suspendduration. The alarm suspend window 500 appears as a portion of a monitordisplay 501, such as the front panel display 120 (FIG. 1) describedabove. The pop-up window 500 responds to a suspend request, such as asilence button 144 (FIG. 1) press. The alarm suspend window 500 has awindow identifier 502 and one or more parameter subsections 510, 520.Each parameter subsection 510, 520 has a parameter identifier 512, 522and corresponding suspend duration options 514, 524. In an embodiment,specific suspend times are selected via monitor touch keys 130 (FIG. 1)as guided by corresponding touch key icons 560. Selected suspend timesare highlighted or otherwise identified and entered, also via a touchkey 130 (FIG. 1). In an alternative embodiment, the monitor display is atouch screen and alarm suspend times are directly entered by a fingerpress on a specific duration “virtual button” 514, 524. Once one or moresuspend durations are entered, the pop-up window 500 disappears from thedisplay 501. The alarm suspend window 500 advantageously allows a userto quickly choose an appropriate alarm suspend duration for thesituation at hand, rather than relying on a predetermined or defaultduration.

An alarm suspend system is described above with respect to alarmstriggered by measured parameters and limits associated with thosemeasured parameters. Limits may correspond to levels of a measuredparameter, such as a percentage oxygen saturation to name but oneexample. Limits may also correspond to trends of a measured parameter,such as a rate-of-change of oxygen saturation, for example. Limits mayalso correspond to patterns in a measured parameter or a comparison ofone measured parameter with another measured parameter, as furtherexamples.

An alarm suspend system is described above with respect to a two-tiergrouping of parameters, such as slow treatment and fast treatmentparameters and alarm suspend durations associated with those groups.Groupings of parameters with respect to alarm suspend durations may bemulti-tier, such as slow, medium and fast treatment parameters, to namebut one example.

An alarm suspend system has been disclosed in detail in connection withvarious embodiments. These embodiments are disclosed by way of examplesonly and are not to limit the scope of the claims that follow. One ofordinary skill in the art will appreciate many variations andmodifications.

What is claimed is:
 1. A physiological measurement system comprising: aphysiological sensor including: a plurality of light emitting diodesconfigured to transmit wavelengths of light onto a tissue site of apatient; and at least one detector configured to measure an indicationof the wavelengths of light after attenuation by tissue of the patientand output a signal responsive of the attenuated light; one or moreprocessors in communication with the physiological sensor, the one ormore processors configured to: determine a measurement of aphysiological parameter based on the signal; in response to determiningan alarm activation threshold has been satisfied by the physiologicalparameter measurement, activate an alarm; in response to a silencerequest by a user, suspend the alarm for a parameter-specific period oftime; and before expiration of the parameter-specific period of time,and in response to determining the physiological parameter measurementno longer satisfies the alarm activation threshold, deactivate thesuspended alarm.
 2. The physiological measurement system of claim 1,wherein the one or more processors are further configured to: determinea second physiological parameter measurement based on the signal; inresponse to determining a second alarm activation threshold has beensatisfied by the second physiological parameter measurement, activate asecond alarm; in response to a second silence request by a user, suspendthe second alarm for a second parameter-specific period of time, thesecond parameter-specific period of time different from theparameter-specific period of time; and before expiration of the secondparameter-specific period of time, and in response to determining thesecond physiological parameter measurement no longer satisfies thesecond alarm activation threshold, deactivate the suspended secondalarm.
 3. The physiological measurement system of claim 1, wherein theparameter-specific period of time is associated with the physiologicalparameter.
 4. The physiological measurement system of claim 3, whereinthe parameter-specific period of time is stored in a memory device incommunication with the one or more processors.
 5. The physiologicalmeasurement system of claim 1, wherein determining the physiologicalparameter measurement no longer satisfies the alarm activation thresholdcomprises determining no physiological data is received from the signal.6. The physiological measurement system of claim 1, wherein determiningthe physiological parameter measurement no longer satisfies the alarmactivation threshold comprises determining a condition of the patienthas improved.
 7. The physiological measurement system of claim 1,wherein the alarm activation threshold comprises a physiologicalparameter limit.
 8. The physiological measurement system of claim 1,wherein the alarm activation threshold comprises a physiologicalparameter trend.
 9. The physiological measurement system of claim 1,wherein the alarm activation threshold comprises a physiologicalparameter pattern.
 10. An method comprising: measuring a physiologicalparameter using a patient monitoring device, the patient monitoringdevice including a processor and a memory device configured to store aparameter-specific alarm suspension period of time; in response todetermining an alarm activation threshold has been satisfied by thephysiological parameter measurement, activating an alarm; in response toa silence request by a user, suspending the alarm for theparameter-specific alarm suspension period of time; and beforeexpiration of the parameter-specific alarm suspension period of time,and in response to determining the physiological parameter measurementno longer satisfies the alarm activation threshold, deactivating thesuspended alarm.
 11. The method of claim 10, wherein the alarm includesan audible component and a visual component, and wherein suspending thealarm comprises suspending the audible component and not suspending thevisual component.
 12. The method of claim 10 further comprising:measuring a second physiological parameter using the patient monitoringdevice, the memory device further configured to store a secondparameter-specific alarm suspension period of time; in response todetermining a second alarm activation threshold has been satisfied bythe second physiological parameter measurement, activating a secondalarm; in response to a second silence request by a user, suspending thesecond alarm for the second parameter-specific alarm suspension periodof time; and before expiration of the second parameter-specific alarmsuspension period of time, and in response to determining the secondphysiological parameter measurement no longer satisfies the second alarmactivation threshold, deactivating the suspended second alarm.
 13. Themethod of claim 10, wherein the parameter-specific alarm suspensionperiod of time is associated with the physiological parameter.
 14. Themethod of claim 10, wherein determining the physiological parametermeasurement no longer satisfies the alarm activation threshold comprisesdetermining no physiological data is received from the patientmonitoring device.
 15. The method of claim 10, wherein determining thephysiological parameter measurement no longer satisfies the alarmactivation threshold comprises determining a condition of a patient hasimproved.
 16. The method of claim 10, wherein the alarm activationthreshold comprises at least one of: a physiological parameter limit, aphysiological parameter trend, or a physiological parameter pattern. 17.The method of claim 10, wherein the physiological parameter comprisesoxygen saturation.
 18. A physiological measurement system comprising: aphysiological sensor means for outputting a signal responsive to anoninvasive measurement of attenuated light transmitted through a tissuesite of a patient; and a processing means in communication with thephysiological sensor means and configured to: determine a measurement ofa physiological parameter based on the signal; in response todetermining an alarm activation threshold has been satisfied by thephysiological parameter measurement, activate an alarm; in response to asilence request by a user, suspend the alarm for a parameter-specificperiod of time; and before expiration of the parameter-specific periodof time, and in response to determining the physiological parametermeasurement no longer satisfies the alarm activation threshold,deactivate the suspended alarm.
 19. The physiological measurement systemof claim 18, wherein the processing means is further configured to:determine a second physiological parameter measurement based on thesignal; in response to determining a second alarm activation thresholdhas been satisfied by the second physiological parameter measurement,activate a second alarm; in response to a second silence request by auser, suspend the second alarm for a second parameter-specific period oftime, the second parameter-specific period of time different from theparameter-specific period of time; and before expiration of the secondparameter-specific period of time, and in response to determining thesecond physiological parameter measurement no longer satisfies thesecond alarm activation threshold, deactivate the suspended secondalarm.
 20. The physiological measurement system of claim 18, whereindetermining the physiological parameter measurement no longer satisfiesthe alarm activation threshold comprises determining no physiologicaldata is received from the signal.